Variable volume sampling chamber



Aug. 31, 1965 E. J. BlCEK VARIABLE VOLUME SAMPLING CHAMBER Filed Jan. 8, 1962 lgure Figure 2 Figure 3 nnnnn INVENTOR: Edward J. Bicek BK- E Z A TTOR/VEYS United States Patent 3,203,247 VARIABLE VOLUME SAMPLING CHAMBER Edward J. Block, La Grange, Ill., assignor to Universal Oil Products Company, Des Plaines, 111., a corporation of Delaware Filed Jan. 8, 1962, Ser. No. 164,701 1 Claim. (Cl. 73-421) The present invention relates to an improved type of fluid sampling chamber having an expansible section in connection therewith and more specifically with a sample chamber construction incorporating a bellows wall section which provides a resulting variable volume chamber that permits easy displacement of a fluid sample from the chamber.

One of the major problems in the use of present types of sampling chambers is the obtainment of a liquid or gaseous fluid sample from the chamber without effecting a loss or contamination thereof. With a rigid container, containing a gas sample at atmospheric pressure, it is necessary to heat the chamber or introduce a displacement liquid medium such as salt water, mercury, etc., in order to effect at least a partial displacement and removal of a sample of the fluid to be tested. In effecting the displacement operation, there is usually contamination of the fluid medium being sampled or an unnecessary loss in quantity. In still other instances, a change in temperature or atmospheric pressure will effect a change in a liquid sample, by causing either vaporization or condensation of some portions thereof, and a resulting change in composition. Liquid samples in a flexible wall or variable volume chamber will remain substantially unchanged as the chamber accommodates itself to atmospheric changes. This is not possible in a rigid container unless the chamber is fitted with unusually good valves which entirely preclude vapor passage. For example, in the sampling of a liquid hydrocarbon stream for dissolved oxygen content, it is absolutely necessary that there be no vapor phase eflected in the sampling chamber or any loss therefrom by reason of temperature or pressure changes while being shipped or stored.

It is a principal object of the present invention to provide a flexible wall means for assisting in the discharge of a fluid sample from the sampling chamber.

It is also an object of the present invention to provide a flexible wall section in combination with the sample chamber such that a resulting variable volume chamber is effective to eliminate errors and contamination when removing a sample stream, or from vapor phase formation by reason of minor atmospheric or temperature changes.

In a broad embodiment, the present invention provides a variable volume sampling chamber having flexible fluid displacement means operative therewith to remove and discharge a fluid sample from the chamber, which comprises, in combination, a confined chamber having valving means at opposing ends thereof adapted to receive and retain a fluid sample therein, a compressible and expansible corrugated wall bellows section attached to the wall of said chamber in a position to have exposure to the fluid sample entering said sample chamber.

In a specific embodiment, a bellows type of wall section may be utilized in combination with the sampling chamber to provide at least a portion of the actual longitudinal wall section of the sampling chamber. The bel- 3,203,247 Patented Aug. 31, 1965 "ice lows wall section is preferably constructed of a relatively thin gauge metal and has a corrugation pitch which permits easy longitudinal movement of such section so that after the sampling chamber has been filled with a gaseous or liquid sample, the chamber may be compressed and a portion of the fluid sample readily discharged. In order to preclude dilution or contamination of the stream being sampled, the flexible wall sampling chamber may be elongated to permit fluid access into the outer sections of the corrugations, or alternatively, the entire sampling chamber may be compressed and expanded a few times during the sampling operation in order to insure the complete purging of any fluid medium which may have been initially present in the chamber at the time of starting up the sampling operation.

Various mechanical means may be provided for compressing and/or expanding the chamber as for example, threaded or geared means attached to the respective ends of the sampling chamber or the use of a mechanically movable shell or cage adapted to encompass the sampling chamber so as to effect the longitudinal expansion and compression as may be desired.

In a somewhat different specific embodiment of the apparatus, a compressible and expansible bellows section may be placed internally within the sampling chamber in a manner to be surrounded by and acted upon by the fluid stream being sampled. In the operation of this type of sampling chamber, the fluid stream entering the sampling chamber would eflfect the compression of the internal bellows section so that subsequently, at the time of the withdrawal of the sample from the chamber, the compressed internal bellows section will be permitted to expand and displace a portion of the fluid stream. This latter modification is primarily adapted for use in the sampling of high pressure fluid streams where the sampling procedure is at superatmospheric conditions. In combination with the internally positioned bellows section, there may be utilized a valved passageway or opening to the interior of the bellows section, such that the latter may be pressured to any desired level which may be subatmospheric or superatmospheric.

Reference to the accompanying drawing and the following description thereof will serve to further illustrate the construction and arrangement of the improved type of sampling chamber, as well as illustrate further advantages possible through the use of a variable volume chamber in sampling operations.

FIGURE 1 of the drawing is a diagrammatic elevational view of one embodiment of a sampling chamber having an exterior bellows wall section.

FIGURE 2 of the drawing is a sectional view through the embodiment of FIGURE 1, as indicated by the line 2-2.

FIGURE 3 of the drawing is an elevational view, partially in section, showing an embodiment having an internally positioned flexible bellows wall section connecting to the internal wall of the chamber and having a valved passageway through the chamber wall.

Referring now to FIGURES 1 and 2 of the drawing, there is indicated a sampling chamber wall section 1 having connected theerto and forming a part of the longitudinal wall thereof, a bellows section 2. The end of the latter is connected with an end closure plate 3, which is provided with an end fluid passageway section 4 in turn connecting with a valve 5. The end portion is of wall section 1 is likewise provided with an end passageway section 6 connecting to a valve 7.

The two opposing valves and 7 permit the sampling chamber to be connected with any desired process vessel or pipe line in order to receive a flow of a fluid stream to be sampled. Generally, the downstream valve will be opened for a period of time during the procedure to insure complete filling of the sample chamber and the discharge and purging of any residual fluid or gaseous material that may be initially inside the sample chamber. As hereinbefore indicated, to insure the obtention of a pure sample the chamber may be compressed and expanded to effect the complete filling of the corrugated wall section 2 by the sample fluid.

In order to assist in the compression and expansion of the flexible wall bellows section 2, there is indicated a pair of longitudinal eye bolts 8 which are positioned and attached to diametrically opposed portions of the sample chamber. The eye ends of bolts 8 are attached to projecting rods or stud bolts 9 at one end of the chamber, with suitable retaining nuts 10 being used to hold the eye bolts in place. At the opposing end of the chamber, suitable slotted shoulder members 11 connect to opposing sides of the chamber wall section 1 and are adapted to receive grooved shoulder sections of wing nuts 12. The slots in the projecting sections 11 are sized to accommodate a turning fit of the grooved shoulder portions of the wing nuts 12, so that as the latter are turned on the threaded shaft sections of the eye bolts 8 there is a resulting shortening or lengthening of the chamber at the bellows section 2.

It should be pointed out that the threaded eye bolt arrangement, together with the slotted plate and wing nut construction, is merely one embodiment for eifecting compression and expansion of the flexible wall section of the chamber and that other suitable mechanical means may be utilized to effect longitudinal movement of the chamber wall. For example, a spirally threaded rod, with crank means at one end, being positioned to engage a fixed threaded bearing attached to the wall of the chamber may provide a mechanical equivalent for compresssing or expanding the wall section. Also as noted hereinbefore, a suitable encompassing shell or cage-like means with geared or threaded movement means may be used to longitudinally expand and compress the bellows section of the sampling chamber. It i also within the scope of the present invention to utilize a sampling chamber having substantially the entire longitudinal wall section of a corrugated bellows like construction.

In order to make the sampling chamber of FIGURE I manually compressible it is desirable to have a relatively thin gauge bellows section, say of the order of 3 to 10 mills in thickness for a diameter in the range of from two to four inches. At the same time the distance or pitch between corrugations should be relatively small, say of the order of 1 to /2 inch. For larger diameter sampling chambers, the thickness of metal may be somewhat greater and the pitch somewhat larger and expansibility and compressibility still retained within limits to permit easy movement of the chamber. Generally, a preferred form of chamber will be constructed of stainless steel, however, where a particular unit is to be used for a particular type of operation, a special metal which may be other than stainless steel can be adopted and used to suit the fluid being sampled in order to preclude corrosion of the chamber or contamination of the fluid stream. Referring now to FIGURE 3 of the drawing there is indicated a modified embodiment particularly adapted to sample fluid streams under high superatmospheric conditions. Such embodiment having a strong, rigid and confined chamber section 13 that is provided with suitable end passageway sections 14 and 15. The latter are indicated as being tapped to accommodate suitable pressure holding valves 16 and 17.

Mounted internally within the chamber section 13 is a hollow flexible wall bellows unit 18 having end closure plates 19 and 20. The bellows unit is welded or otherwise attached to a spacer plate 21 along the inside wall of the chamber 13. Plates 20 and 21, as well as the side wall of the chamber 13 are provided with gas passageway openings to provide a passage 22 communicating between the interior of the bellows unit 18 and a valve 23. The openings in the wall of chamber 13 and spacer plate 21 may be tapped or threaded to accommodate the valve 23 to in turn provide a screwed connection of the latter to the unit.

The present sample chamber may be used in a conventional manner to obtain a fluid sample by attaching one of the end valve-s to a process vessel or pipe line containing the fluid medium to be sampled and permitting both valves to remain open until such time as the chamber is purged and a pure sample is obtained. The inner confine-d bellows section 18 will normally be at atmospheric pressure so that as a fluid medium under pressure is introduced into the housing 13 the bellows section 18 will be compressed in accordance with the extent of the superatmospheric pressure of the fluid medium, such compression being retained until time for releasing at least a portion of the sample fluid from the container for analysis purposes. vThus, the internal bellows section provides a convenient desirable means for permitting variations in the internal volume of the sample chamber to accommodate variations in pressure or temperature that may be encountered by the chamber in transit or in storage.

As has been pointed out hereinbefore, there is a distinct advantage in having a sampling chamber that can accommodate volumetric changes in order that the fluid sample is not changed from a liquid to vaporous state due to external conditions. Of particular importance, of course, is the advantage of being able to discharge a fluid sample without contamination. When desired, in connection with the embodiment of FIGURE 3, the internal bellows 18 may be physically expanded by introducing pressure from an extraneous fluid pressure source through valve 23 and passageway 22 into the interior of the bellows section.

In order to have the internal bellows section 18 flexible it is generally desirable to construct the corrugations of the bellows of a relatively thin gauge metal and have the corrugations of a suflicient height and pitch to permit good flexure characteristics, as set forth in the embodiment of FIGURE 1.

For atmospheric pressure sampling, the embodiment of FIGURE 1 is convenient and very satisfactory; however, the embodiment of FIGURE 3 is of a better design than FIGURE 1 from the aspect of accommodating high pressure conditions. Although by the use of suitable guide or enclosure means, it is possible to utilize the design of FIG- URE 1 under relatively high pressure conditions without encountering rupturing or excessive deformation of the bellows section. Also, where it is deemed desirable in the embodiment of FIGURE 3, suitable encompassing and guide means may be provided for the exterior of the bellows 18 within the chamber 13. It may also be pointed out that the location of the bellows section 18 within the chamber 13 may be varied, as for example, it may be connected to an end section rather than to a portion of the circumferential wall where it extends substantially at right angles to the fluid flow. In another arrangement, it is possible to position the bellows section so that a portion of it extends exteriorly from the wall of the housing 13; however, a preferred construction maintains the entire bellows section internally within the unit such that it may be encompassed and acted upon by the pressure of the fluid stream being sampled. Still, further, it may be pointed out that additional tubing or valving means may be provided for the sample chambers for use in physically connecting analysis equipment, and in some cases it may be desirable to have the chamber wall fitted with a hypodermic syringe or needle connection to provide for the direct discharge of a small quantity of sample fluid from the unit.

I claim as my invention:

A variable volume sample chamber having flexible fluid displacement means operative to move and discharge a fluid sample from the chamber, comprising in combination, a confined metal wall chamber having separate fluid inlet and outlet valving means connecting therewith, a compressible and expansible corrugated metal wall bellows section forming at least a part of the exterior wall portion of said sample chamber whereby the interior of such section is exposed to and acted upon by the fluid sample entering the chamber, and adjustable threaded means said bellows section, whereby the latter may be compressed or expanded by the adjustment of said threaded means and a fluid sample readily discharged.

References Cited by the Examiner UNITED STATES PATENTS 1,752,085 3/30 Hinkle 222-212 X 2,529,937 11/50 Hale 73269 X FOREIGN PATENTS 1,014,346 Germany.

RICHARD C. QUEISSER, Primary Examiner.

extending between opposing ends of said chamber across 15 RQBERT EVANS, Examiner- 

